title: Increased resting functional connectivity in spike-wave epilepsy in WAG/Rij rats.
abstract: OBJECTIVE
  Functional magnetic resonance imaging (fMRI)-based resting functional connectivity is well suited for measuring slow correlated activity throughout brain networks. Epilepsy involves chronic changes in normal brain networks, and recent work demonstrated enhanced resting fMRI connectivity between the hemispheres in childhood absence epilepsy. An animal model of this phenomenon would be valuable for investigating fundamental mechanisms and testing therapeutic interventions.
  
  
  METHODS
  We used fMRI-based resting functional connectivity for studying brain networks involved in absence epilepsy. Wistar Albino Glaxo rats from Rijswijk (WAG/Rij) exhibit spontaneous episodes of staring and unresponsiveness accompanied by spike-wave discharges (SWDs) resembling human absence seizures in behavior and electroencephalography (EEG). Simultaneous EEG-fMRI data in epileptic WAG/Rij rats in comparison to nonepileptic Wistar controls were acquired at 9.4 T. Regions showing cortical fMRI increases during SWDs were used to define reference regions for connectivity analysis to investigate whether chronic seizure activity is associated with changes in network resting functional connectivity.
  
  
  RESULTS
  We observed high degrees of cortical-cortical correlations in all WAG/Rij rats at rest (when no SWDs were present), but not in nonepileptic controls. Strongest connectivity was seen between regions most intensely involved in seizures, mainly in the bilateral somatosensory and adjacent cortices. Group statistics revealed that resting interhemispheric cortical-cortical correlations were significantly higher in WAG/Rij rats compared to nonepileptic controls.
  
  
  CONCLUSIONS
  These findings suggest that activity-dependent plasticity may lead to long-term changes in epileptic networks even at rest. The results show a marked difference between the epileptic and nonepileptic animals in cortical-cortical connectivity, indicating that this may be a useful interictal biomarker associated with the epileptic state.
authors.affiliation: Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 6520-8018, USA.
authors.forename: Asht M
authors.initials: AM
authors.lastname: Mishra
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Bai
authors.forename: Joshua E
authors.initials: JE
authors.lastname: Motelow
authors.forename: Matthew N
authors.initials: MN
authors.lastname: Desalvo
authors.forename: Nathan
authors.initials: N
authors.lastname: Danielson
authors.forename: Basavaraju G
authors.initials: BG
authors.lastname: Sanganahalli
authors.forename: Fahmeed
authors.initials: F
authors.lastname: Hyder
authors.forename: Hal
authors.initials: H
authors.lastname: Blumenfeld
mesh_terms: D000818:Animals; D001921:Brain / Q000098:blood supply / Q000473:pathology* / Q000503:physiopathology*; D001931:Brain Mapping; D058256:Brain Waves / Q000502:physiology*; D004195:Disease Models, Animal; D004569:Electroencephalography; D004832:Epilepsy, Absence / Q000235:genetics / Q000473:pathology*; D007839:Functional Laterality; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D009434:Neural Pathways / Q000098:blood supply / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D051381:Rats; D011922:Rats, Mutant Strains; D017208:Rats, Wistar; D012146:Rest / Q000502:physiology*; D013223:Statistics as Topic
chemical_list: D010100:Oxygen
keywords: Cortex; Functional magnetic resonance imaging; Resting functional connectivity; Spike-wave seizure; Thalamus